The invention relates to a process for making 5-amino-1,2,3,-thiadiazoles.
Two processes are already known for making these compounds.
One process is based on a reaction of diazomethane with acyl mustard oil (J. Goerdeler and G. Gnad, Ber. 99, 1618, 1966). Considering the explosive nature and toxicity of the diazomethane and the low yield of about 32% this process has not been found useful for industrial production of the 5-amino-1,2,3,-thiadiazoles.
The other process involves a sequence of seven reaction steps wherein the amino group is introduced into the thiadiazole ring through a so-called Gabriel synthesis, that is, in the form of an amino protective group (a phthalimido residue), see D. L. Pain and R. Slack, J. Chem. Soc. 5166-76, 1965. This process likewise is not suited for industrial production since it is rather costly because of the seven reaction steps and also had only a low yield of about 35% and furthermore involves formation of phthalic acid hydrazide for which there is no further use. It also requires large capacity vessels and high amounts of energy.
It is therefore an object of the present invention to provide a process for making 5-amino-1,2,3-thiadiazoles in comparatively few steps and with good yields and thus to provide for an industrially useful method of making these compounds.